you can "build" your own... but the idea behind both these saws is that the blade spins upward/backward. thus pinching the material between the guide and the blade. there is no fray or splintering at all. also the zero measurement is a real time saver. you can mark your cut with a tiny fine point sharpie or highly sharpened pencil and cut to with in 1/128. there is no offset.
i have the ts75. i got it because i wanted to reverse bevel cut very deep pieces after mounting (kind of a faux compound cut). the dewalt and smaller ts55 are much smaller. the ts75 is a beast. very powerful (can cut four or five 3/4 sheet of plywood at once). but it weighs too much for extended cutting at a lower depth on lighter material. i've considered picking up a ts55 on ebay for $300 which i'd use for probably 90% of my cutting.
the dewalt has the "both directions" guide. that is a real plus. doesn't seem like much. but when you get in a "just how fast can i knock down all the material" mode. you can get frustrated when you're all set up. and then you realize that you are on the "wrong side" of your table. with the dewalt, there is no such thing as "wrong side". if i was handing an employee a track saw and i wanted maximum speed. the dewalt would probably win from shear less "thinking" and more cutting per hour.
all in all, in the past needing to cut down large heavy sheets, or... very lightweight sheets, or acrylic, or the long 10' side of aluminum (my shear is only 52"), or very valuable material, there was always a bit of anxiety... "i really gotta make this cut good or i will be screwed". now cutting the most valuable material, it's not uncommon to look away while cutting and give orders to a guy, pointing out which sheet is next, or to grab the measuring tape, because you just can't mess up a cut with this. the saw digs in and "grabs" the material, cut laser straight, perfectly square. ...hate to say this. it's sounds sexist... i even let my girlfriend use it to cut material. it's the only saw that she's get near. that is how easy it is so use.
i can't imagine a panel saw having an advantage over a track saw except for in a construction environment. you could set up stops and maybe knock down osb all day long. but for fabrication where perfection is necessary, the track saw is the "surgeons saw".
in the attached picture, this piece is a $5000 piece, blind cut after mounting the image (etched and printed aluminum, mounted to 4" deep pine beams). so yes, the entire image plus base was cut in one pass at an angle. you would be crazy to risk a part like this by putting it in a saw. but i plopped the guide down on the whole thing and chopped off the chamfered edges. no scratches, and the edges of the wood looked like i'd sanded them with 200 grit. perfect smooth toothless cut.